1. Field of the Invention
The present invention relates to a holder for an end face grinding (polishing) apparatus that simultaneously grinds a plurality of end faces of optical fiber ferrules.
2. Description of Related Art
Generally, this type of end face grinding apparatus includes a turntable that rotates horizontally, with a circular grinding film placed thereon. A holder (grinding jig) that holds a plurality of optical fiber ferrules is then mounted on the end face grinding apparatus. By turning the turntable, the end faces of all optical fiber ferrules are ground simultaneously by the grinding film.
The holder used for such an end face grinding apparatus includes a plurality of insertion holes into which each optical fiber ferrule is inserted, and holds the respective optical fiber ferrules while each optical fiber ferrule is inserted into each insertion hole and positioned therein.
Conventional holders have a plurality of insertion holes, into which each optical fiber ferrule is inserted, arranged annularly (circularly) around a round hole formed at the center, and the insertion holes are formed on the annular circumference with an equal interval. This type of holder is disclosed in Japanese Patent Application Laid-Open No. 2003-53652.
However, the conventional holder for an optical fiber ferrule end face grinding apparatus has problems as described below.
That is, as shown in FIG. 1, when a grinding film 164 is rotated with respect to the optical fiber ferrules arranged annularly on a holder 110, the grinding track on the grinding film leaves a relatively wide unused area at the center, thereby wasting this part.
Since the circumferential length of one circle is fixed, even if it is tried to arrange the optical fiber ferrules as many as possible on the circumference thereof, there is naturally a limitation.
Furthermore, since all the optical fiber ferrules follow along the same grinding track, abrasive grains only in the track portion on the grinding film wear out extremely, thereby reducing the service life of the grinding film.
These are the cause of high grinding cost per one optical fiber ferrule.
As a result of all the optical fiber ferrules following along the same grinding track, as the grinding film repeats grinding, a step appears in a boundary portion between the track portion and the unused portions at the opposite sides thereof. Due to the step in the boundary portion, nonuniform grinding force may be generated on the ferrule end face, thereby deteriorating the grinding quality.